DNA & Protein Synthesis Vocabulary: DNA Nucleotide Base Pairing Messenger RNA (mRNA) Ribosomal RNA (rRNA) Transfer RNA (tRNA) Transcription Polymerase Promoter Intron Exon Codon Translation Anticodon

DNA DeoxyRibo-Nucleic Acid A molecule made up of nucleotide base pairs which determines the genetic make-up of an organism

What DNA does… Carries information from one generation to the next Put that information to work by determining heritable characteristics Must be easily copied since almost every new cell gets a copy

DNA Structure Made up of nucleotides Each composed of 3 parts: Deoxyribose: sugar Phosphate group Nitrogenous (nitrogen containing) base Adenine (A) Thymine (T) Guanine (G) Cytosine (C)

Backbone: the sugar groups and the phosphate groups “Steps of Ladder:” connected base pairs Adenine Thymine Guanine Cytosine

How the bases pair in DNA… A T (A pairs with T) C G (C pairs with G)

What’s holding the strands together? HYDROGEN BONDS!!! Hydrogen Bonds will only form between A and T base pairs as well as between C and G base pairs – this is the principle of base pairing

Okay so we have DNA, how does it affect our body’s function? DNA holds the code to help the body make proteins. There are a series of processes that allow for the information contained in DNA to be turned into functional proteins These processes are called transcription and translation

The Importance of Proteins Proteins are diverse! They control chemical messages in cell Direct the synthesis of carbohydrates, lipids and act as enzymes Give the cell structure and movement

Quick Review of Proteins Made of amino acids There are only 20 amino acids to make up a lot of proteins Proteins are a major component of cells Proteins are made in ribosomes

PROTEIN SYNTHESIS DNA Step 1. TRANSCIPTION (nucleus) mRNA Step 2. TRANSLATION (ribosome) tRNA PROTEIN

RNA Like DNA, made of nucleotides Disposable copy of DNA segment 3 differences: 1) sugar= ribose 2) single stranded 3) instead of the base thymine (T), RNA uses uracil (U)

RNA 3 types: mRNA – used in transcription tRNA – used in translation rRNA – component of ribosome

Info about Transcription Step #1 (of 2) of protein synthesis Starts in the nucleus Uses 1 side of DNA as a template Copies 1 gene at a time Makes a section of mRNA

Transcription transcribing DNA information (gene instructions) into mRNA which can leave the nucleus and go to the ribosomes in the cytoplasm messenger RNA= mRNA (1 type of RNA) special base sequences in DNA are recognized by RNA as “start” and “stop” signals “Start” sequence called promoter region of DNA

Details of the Process 1.RNA polymerase attaches to DNA and it separates the 2 DNA strands (unzips the strand)

2. RNA polymerase synthesizes the mRNA strand using complimentary base- pairing

Remember…there aren’t “T” bases in RNA “C” binds with “G” DNA “A” binds with RNA “U”

Which strand was copied? A or B

3. when RNA polymerase reaches the end or "STOP" part of the genetic code for that protein, it releases 4. DNA re-zips   5. finished mRNA (messenger) leaves the nucleus and goes to a ribosome in the cytoplasm

mRNA bases are grouped by 3 Each group of 3 nucleotides are called a codon (“code”)

Review of Transcription Transcription occurs in the nucleus The product of transcription is mRNA Only 1 side of DNA is used as a template & only 1 gene is needed Enzymes regulate the process

Translation Making a protein (string of amino acids) from the information carried by mRNA. Occurs in the ribosome. A group of 3 mRNA bases makes up a “codon” (think of as a “code word”) each codon specifies a particular amino acid there are “start” and “stop” codons

Translation continued mRNA travels from the nucleus and attaches onto the ribosome with codons 3 nucleotides of mRNA = codon 2nd kind of RNA= ribosomal RNA (rRNA) makes up the majority of the ribosome

Translation continued 3rd kind of RNA= transfer RNA (tRNA) carries amino acids to the ribosomes (amino acids join together to form proteins) there are 64 different tRNA molecules (more than 1 for each amino acid) 3 nucleotides of tRNA that “match” or compliment the mRNA = anticodon

Translation continued By matching the codon of mRNA to the anticodon of tRNA, the correct amino acid is put into place, then tRNA releases and leaves the amino acid in place. Next tRNA goes here!!!!

amino acid tRNA anticodon codon (mRNA)

the protein is now finished & released!!

PROTEIN SYNTHESIS: All At Once

The genetic code …is a correlation between the codon on mRNA and an amino acid …there are stop & start codons

The Genetic code Third letter

Review of Translation Purpose is to make bring amino acids to the ribosomes to make proteins. Translation occurs on the ribosomes as tRNA delivers amino acids. This occurs as the anticodons on the tRNA match up with the codons of the mRNA. A start codon begins the process. Once the amino acids are delivered the tRNA leaves and gathers more. The stop codon ends the process and the amino acid chain makes a protein.